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We are a military family attached to a base located south of Tokyo. Last month we were evacuated back to the US in light of the events at TEPCOs Fukushima Daiichi plant. We are not authorized to return until they determine it is safe. (BTW, they have not told us what the criteria is for “safe”). I have read that the amount of radiation released is 10% of what was released at Chernobyl, BUT there is a potential for Fukushima Daiichi’s reactors to release the same amount over time. As a parent of two children under the age of 5, what risks (if any) are we facing once we return? Thank you for the opportunity to post a question.

Although this is not directly related to Fukushima, could you please comment on something that has now been told in several TV documentaries and on the internet about Tchernobyl: that there was the possibility of a second, nuclear explosion that could have had the power of several megatons. This can be found on lots of web pages, one of them this guardian article: http://www.guardian.co.uk/environment/2005/apr/25/energy.ukraine. Scroll down to “Sergei Vasilyevich Sobolev”. I cannot personally see how this would have been possible at all, but maybe you can give some expert insight into this?

The recent data on the Daiichi plant being set at “7”, seems to be strange. I find that there are many websites that are talking about the 1/1oth value of radiation leaked out. I’ve been looking at the various measures of milliseverts vs microseverts, terabecquerels. It actually get confusing. My guess is that there is no threat to people (unless there continues to be more earthquakes, but that is not radiation). Why compare this to Chernobly since standing next to the reactor after it exploded would be an exposure of 50 Sv, and there is nothing even close to this going on at the Daiichi plants?

Unfortunately, radioactive forms of an element differ from their stable (non-radioactive) counterparts only in the number of neutrons inside their atoms. This means that (aside from the radioactivity) the only difference from their stable form is their mass. Consequently, there is no way to chemically filter out just the radioactive forms of an element. They react chemically just the same as their stable forms. (This is the reason why it was so hard to make the first atomic bomb – they had to separate U-235 from U-238, which was and still is an enormously difficult and expensive task, exploiting the very slight difference in mass. The centrifuges you may have heard about in Iran are needed for this step.)

The easiest thing you can do is filter out *all* of the contaminant element – both stable and radioactive isotopes. e.g. Reverse osmosis filtering is very effective at removing almost all contaminants from water. Most bottled water is RO filtered (spring water and mineral water are not). Another method would be to simply allow the water to evaporate, leaving behind the contaminants (note however that iodine can exist as a gas at standard temperature and pressure).

Due to the nature of the Fukushima accident, most of the radioactive contamination is coming from iodine and cesium. Iodine has a relatively short half life (8 days), so within a few months it should decay to negligible levels. Cesium is more problematic (30 year half life), but the amounts being produced by the accident will be negligible compared to natural background radiation once sufficiently dispersed in the ocean. The bigger concern is if it gets into groundwater aquifers (where it cannot disperse – unlikely since the plant is right next to the ocean), or if fish near the plant ingest large quantities of it before it can disperse.

Dear sir,
The incident at Fukushima is a ‘Beyond design bassis accident’ that is called ‘Severe accident’ also. Much before this incident USNRC had issued ‘Severe accident management guidelines’. What these guidelines are? Can you please post copy of these guidelines or mail a copy to me? I will be very greatful to you.
Thanking you,
Singh SK

Question regarding KI tablets, now being offered by foreign embassies to their citizens in Tokyo. Under what conditions would taking KI be advised, and for whom? And for exactly what purpose? (i.e., what would taking KI prevent or cure?)

I have a question about radiation found in milk. I am a mother who is still currently nursing my child. I understand that when cows eat grass that has been contaminated with radiation the radiation gets into their milk in concentrated amounts. So my question for you is, if I drink milk that has very low levels of radiation (as has been found in WA and CA, I live in CA) wont that radiation become even more concentrated in the milk that my body is producing? Any thoughts would be greatly appreciated.

Since the levels at which we’re observing I-131 in cow’s milk are currently thousands times below the point at which the FDA would recommend that people stop drinking milk, you should be fine to keep on breast feeding.